<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta http-equiv="Content-Language" content="zh-cn">
    
    
    <title>
        
            LeetCode笔记-字符串 | Nefelibata
             | Nefelibata
        
    </title>
    <meta name="viewport" content="width=device-width,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no">
    
        <meta name="theme-color" content="#77AAFF">
    
    
    <meta name="keywords" content="Leetcode">
    
    

    

    <!-- Baidu Push -->
<script>
	(function(){
		var bp = document.createElement('script');
		var curProtocol = window.location.protocol.split(':')[0];
		if (curProtocol === 'https') {
			bp.src = 'https://zz.bdstatic.com/linksubmit/push.js';
		}
		else {
			bp.src = 'http://push.zhanzhang.baidu.com/push.js';
		}
		var s = document.getElementsByTagName("script")[0];
		s.parentNode.insertBefore(bp, s);
	})();

	var _hmt = _hmt || [];
</script>



    
    <meta name="description" content="字符串">
<meta property="og:type" content="article">
<meta property="og:title" content="LeetCode笔记-字符串">
<meta property="og:url" content="https://nefelibata.icu/2022/063572401b.html">
<meta property="og:site_name" content="Nefelibata">
<meta property="og:description" content="字符串">
<meta property="og:locale" content="zh_CN">
<meta property="article:published_time" content="2022-06-15T10:15:24.000Z">
<meta property="article:modified_time" content="2024-01-04T02:41:48.347Z">
<meta property="article:author" content="Nefelibata">
<meta property="article:tag" content="Leetcode">
<meta name="twitter:card" content="summary">
    
        <link rel="alternate" type="application/atom+xml" title="Nefelibata" href="/blog/atom.xml">
    
    <link rel="shortcut icon" href="/blog/img/favicon.ico">
    <link id="style" rel="stylesheet" href="/blog/css/style.css?v=3.0">
    <script>window.lazyScripts=[]</script>

    <!-- custom head -->
    
<meta name="generator" content="Hexo 6.3.0">
<style>.github-emoji { position: relative; display: inline-block; width: 1.2em; min-height: 1.2em; overflow: hidden; vertical-align: top; color: transparent; }  .github-emoji > span { position: relative; z-index: 10; }  .github-emoji img, .github-emoji .fancybox { margin: 0 !important; padding: 0 !important; border: none !important; outline: none !important; text-decoration: none !important; user-select: none !important; cursor: auto !important; }  .github-emoji img { height: 1.2em !important; width: 1.2em !important; position: absolute !important; left: 50% !important; top: 50% !important; transform: translate(-50%, -50%) !important; user-select: none !important; cursor: auto !important; } .github-emoji-fallback { color: inherit; } .github-emoji-fallback img { opacity: 0 !important; }</style>
</head>

<body>
    <div id="loading" class="active"></div>
    <aside id="menu"  class >
  <div class="inner flex-row-vertical">
    <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light" id="menu-off">
        <i class="icon icon-lg icon-close"></i>
    </a>
    <div class="brand-wrap" >
      <div class="brand">
        <a class="avatar waves-effect waves-circle waves-light">
          <img src="/blog/img/avatar.jpg" alt="avatar">
        </a>
        <hgroup class="introduce">
          <h5 class="nickname" id="name">Nefelibata</h5>
        </hgroup>
      </div>
    </div>
    <div class="scroll-wrap flex-col">
      <ul class="nav">
        
              <li class="waves-block waves-effect">
                  <a href="/blog/" target="_self" >
                    <i class="icon icon-lg icon-home"></i>
                    <span>主 页</span><i class="icon icon-lg icon-caret-left"></i>
                  </a>
              </li>
            
              <li class="waves-block waves-effect">
                  <a href="/blog/archives" target="_self" >
                    <i class="icon icon-lg icon-archives"></i>
                    <span>归 档</span><i class="icon icon-lg icon-caret-left"></i>
                  </a>
              </li>
            
              <li class="waves-block waves-effect">
                  <a href="/blog/categories" target="_self" >
                    <i class="icon icon-lg icon-th-list"></i>
                    <span>分 类</span><i class="icon icon-lg icon-caret-left"></i>
                  </a>
              </li>
            
              <li class="waves-block waves-effect">
                  <a href="/blog/tags" target="_self" >
                    <i class="icon icon-lg icon-tags"></i>
                    <span>标 签</span><i class="icon icon-lg icon-caret-left"></i>
                  </a>
              </li>
            
              <li class="waves-block waves-effect">
                  <a href="/blog/../gallery" target="_blank" >
                    <i class="icon icon-lg icon-image"></i>
                    <span>相册</span><i class="icon icon-lg icon-caret-left"></i>
                  </a>
              </li>
            
              <li class="waves-block waves-effect">
                  <a href="/blog/../about" target="_blank" >
                    <i class="icon icon-lg icon-smile-o"></i>
                    <span>关 于</span><i class="icon icon-lg icon-caret-left"></i>
                  </a>
              </li>
            
              <li class="waves-block waves-effect">
                  <a href="/blog/../" target="_self" >
                    <i class="icon icon-lg icon-tree"></i>
                    <span>Nefelibata</span><i class="icon icon-lg icon-caret-left"></i>
                  </a>
              </li>
            
      <div class="nav2">
          
              <a class="nav2item" data-title="Email" href="mailto:kunpengl0111@gamil.com" target="_parent"title="Email" >
                <i class="icon icon-lg icon-envelope-o envelope-o"></i>
              </a>
          
              <a class="nav2item" data-title="Github" href="https://github.com/kpl0111" target="_blank"title="Github" >
                <i class="icon icon-lg icon-github github"></i>
              </a>
          
              <a class="nav2item" data-title="Twitter" href="https://twitter.com/Nefelib31847846" target="_blank"title="Twitter" >
                <i class="icon icon-lg icon-twitter twitter"></i>
              </a>
          
        </div>
      </ul>
    </div>
  </div>
</aside>


    <main id="main">
        <header class="top-header" id="header">
    <div class="flex-row">
        <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light on" id="menu-toggle">
          <i class="icon icon-lg icon-navicon"></i>
        </a>
        <div class="flex-col header-title ellipsis">LeetCode笔记-字符串</div>
        
        <div class="search-wrap" id="search-wrap">
            <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light" id="back">
                <i class="icon icon-lg icon-chevron-left"></i>
            </a>
            <input type="text" id="key" class="search-input" autocomplete="off" placeholder="输入感兴趣的关键字">
            <a href="javascript:;" class="header-icon waves-effect waves-circle waves-light" id="search">
                <i class="icon icon-lg icon-search"></i>
            </a>
        </div>
        
        <a href="../../atom.xml" target="_blank" class="header-icon waves-effect waves-circle waves-light" id="Rss">
            <i class="icon icon-lg icon-rss"></i>
        </a>
    </div>
</header>
<header class="content-header post-header">
    <div class="container fade-scale">
        <div id="myheader">
            <h1 class="title">
                
            </h1>
            <h5 class="subtitle">
                
                
            </h5>
        </div>
    </div>
</header>


<div class="container body-wrap">
    
    <aside class="post-widget">
        <nav class="post-toc-wrap" id="post-toc">
            <h4>TOC</h4>
            
                <ol class="post-toc"><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#%E4%BB%80%E4%B9%88%E6%98%AF%E5%AD%97%E7%AC%A6%E4%B8%B2"><span class="post-toc-text">什么是字符串</span></a></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#%E5%8F%8C%E6%8C%87%E9%92%88%E6%B3%95"><span class="post-toc-text">双指针法</span></a></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#KMP"><span class="post-toc-text">KMP</span></a></li></ol>
            
        </nav>
    </aside>
   
<article id="post-LeetCode笔记-字符串"
  class="post-article article-type-post fade" itemprop="blogPost">

    <div class="post-card">
        <h1 class="post-card-title">LeetCode笔记-字符串</h1>
        <div class="post-meta">
            <i class="icon icon-lg icon-calendar-o"></i>
            发表于
            <time class="post-time" title="2022-06-15 18:15:24" datetime="2022-06-15T10:15:24.000Z"  itemprop="datePublished">2022-06-15</time>

            <br id="mybreak"/>
            
	<i class="icon icon-lg icon-folder-o"></i>
	分类：<ul class="article-category-list"><li class="article-category-list-item"><a class="article-category-list-link" href="/blog/categories/%E7%AC%94%E8%AE%B0/">笔记</a></li></ul>


            <i>·</i>
        </div>
        <div class="post-count-custom">
            <i class="icon icon-lg icon-comment-o"></i>
            阅读本文可能花费您&nbsp;<span class="post-count">2.2</span>&nbsp;分钟
        </div>
        <div class="post-content" id="post-content" itemprop="postContent">
            <p>字符串</p>
<span id="more"></span>

<blockquote>
<p>本篇为个人笔记，内容或有错误。<br>图片部分源于<a target="_blank" rel="noopener" href="https://programmercarl.com/">代码随想录</a>，侵删。</p>
</blockquote>
<h3 id="什么是字符串"><a href="#什么是字符串" class="headerlink" title="什么是字符串"></a>什么是字符串</h3><p>字符串是若干字符组成的有限序列，也可以理解为是一个字符数组，但是很多语言对字符串做了特殊的规定。</p>
<p>在C语言中，把一个字符串存入一个数组时，也把结束符 ‘\0’存入数组，并以此作为该字符串是否结束的标志。</p>
<p>例如这段代码：</p>
<pre><code class="C++">char a[5] = "asd";
for (int i = 0; a[i] != '\0'; i++) {
}
</code></pre>
<p>在C++中，提供一个string类，string类会提供 size接口，可以用来判断string类字符串是否结束，就不用’\0’来判断是否结束。</p>
<p>例如这段代码:</p>
<pre><code class="C++">string a = "asd";
for (int i = 0; i &lt; a.size(); i++) {
}
</code></pre>
<p>那么vector&lt; char &gt; 和 string 又有什么区别呢？</p>
<p>其实在基本操作上没有区别，但是 string提供更多的字符串处理的相关接口，例如string 重载了+，而vector却没有。</p>
<p>所以想处理字符串，我们还是会定义一个string类型。</p>
<h3 id="双指针法"><a href="#双指针法" class="headerlink" title="双指针法"></a>双指针法</h3><p>双指针法在数组，链表和字符串中很常用。其实很多数组填充类的问题，都可以先预先给数组扩容带填充后的大小，然后在从后向前进行操作。</p>
<h3 id="KMP"><a href="#KMP" class="headerlink" title="KMP"></a>KMP</h3><p>KMP的主要思想是当出现字符串不匹配时，可以知道一部分之前已经匹配的文本内容，可以利用这些信息避免从头再去做匹配了。</p>
<p>KMP的精髓所在就是前缀表</p>
<p>前缀表：起始位置到下标i之前（包括i）的子串中，有多大长度的相同前缀后缀。</p>
<p>那么使用KMP可以解决两类经典问题：</p>
<ul>
<li>匹配问题：28. 实现 strStr()</li>
<li>重复子串问题：459.重复的子字符串</li>
</ul>
<p>再一次强调了什么是前缀，什么是后缀，什么又是最长相等前后缀。</p>
<p>前缀：指不包含最后一个字符的所有以第一个字符开头的连续子串。</p>
<p>后缀：指不包含第一个字符的所有以最后一个字符结尾的连续子串。</p>
<p>然后针对前缀表到底要不要减一，这其实是不同KMP实现的方式，在KMP精讲 中针对之前两个问题，分别给出了两个不同版本的的KMP实现。</p>
<p>其中主要理解j=next[x]这一步最为关键！</p>

        </div>

        <blockquote class="post-copyright">
    <div class="content">
        
<span class="post-time">
    最后更新：<time datetime="2024-01-04T02:41:48.347Z" itemprop="dateUpdated">2024-01-04 10:41:48</time>
</span>


        
        
        
    </div>
    <footer>
        <div onclick="location.href='https://nefelibata.icu'">
            <img src="/blog/img/avatar.jpg" alt="Nefelibata">
            <a>Nefelibata</a>
        </div>
    </footer>
</blockquote>

        
    <div class="page-reward">
        <nav class="myreward">
            <a id="rewardBtn" href="javascript:;"><span>打&nbsp;赏</span><span>装成好像很多人打赏的样子</span></a>
        </nav>
    </div>



        <div class="post-footer">
            
	<ul class="article-tag-list" itemprop="keywords"><li class="article-tag-list-item"><a class="article-tag-list-link" href="/blog/tags/Leetcode/" rel="tag">Leetcode</a></li></ul>


            
<div class="page-share-wrap">
    

<div class="page-share" id="pageShare">
    <ul class="reset share-icons">
      <li>
        <a class="weibo share-sns" target="_blank" href="http://service.weibo.com/share/share.php?url=https://nefelibata.icu/2022/063572401b.html&title=《LeetCode笔记-字符串》 — Nefelibata&pic=https://nefelibata.icu/img/avatar.jpg" data-title="微博">
          <i class="icon icon-weibo"></i>
        </a>
      </li>
      <li>
        <a class="weixin share-sns wxFab" href="javascript:;" data-title="微信">
          <i class="icon icon-weixin"></i>
        </a>
      </li>
      <li>
        <a class="qq share-sns" target="_blank" href="http://connect.qq.com/widget/shareqq/index.html?url=https://nefelibata.icu/2022/063572401b.html&title=《LeetCode笔记-字符串》 — Nefelibata&source=字符串" data-title=" QQ">
          <i class="icon icon-qq"></i>
        </a>
      </li>
      <li>
        <a class="facebook share-sns" target="_blank" href="https://www.facebook.com/sharer/sharer.php?u=https://nefelibata.icu/2022/063572401b.html" data-title=" Facebook">
          <i class="icon icon-facebook"></i>
        </a>
      </li>
      <li>
        <a class="twitter share-sns" target="_blank" href="https://twitter.com/intent/tweet?text=《LeetCode笔记-字符串》 — Nefelibata&url=https://nefelibata.icu/2022/063572401b.html&via=https://nefelibata.icu" data-title=" Twitter">
          <i class="icon icon-twitter"></i>
        </a>
      </li>
      <li>
        <a class="google share-sns" target="_blank" href="https://plus.google.com/share?url=https://nefelibata.icu/2022/063572401b.html" data-title=" Google+">
          <i class="icon icon-google-plus"></i>
        </a>
      </li>
    </ul>
 </div>



    <a href="javascript:;" id="shareFab" class="page-share-fab waves-effect waves-circle">
        <i class="icon icon-share-alt icon-lg"></i>
    </a>
</div>



        </div>
    </div>

    
<nav class="post-nav flex-row flex-justify-between">
  
    <div class="waves-block waves-effect prev">
      <a href="/blog/2022/06c54e8d28.html" id="post-prev" class="post-nav-link">
        <h4 class="title" >
          上一篇：LeetCode笔记-双指针大法
        </h4>
      </a>
    </div>
  

  
    <div class="waves-block waves-effect next">
      <a href="/blog/2022/06e8411ac8.html" id="post-next" class="post-nav-link">
        <h4 class="title" data-hover="下一篇：LeetCode笔记-KMP">下一篇：LeetCode笔记-KMP</h4>
      </a>
    </div>
  
</nav>


</article>

</div>

        <footer class="footer">
    <div class="footer-content">
        <span class="power">
            <i class="icon icon-lg icon-copyright"></i>
            2021
            <i class="icon icon-lg icon-heart"></i>
            <a href="https://nefelibata.icu">nefelibata.icu</a>
        </span>
    </div>
</footer>

    </main>
    
        
<div id="reward" class="page-modal reward-lay">
    <a class="close" href="javascript:;"><i class="icon icon-close"></i></a>
    <h3 class="reward-title">
        <i class="icon icon-quote-left"></i>
        <span>感谢您的鼓励支持！</span>
        <i class="icon icon-quote-right"></i>
    </h3>
    <div class="reward-content">
        
        <div class="reward-code">
            <img id="rewardCode" data-img="/blog/img/dog.png" alt="打赏二维码">
        </div>
        
        <label class="reward-toggle">
            <input id="rewardToggle" type="checkbox" class="reward-toggle-check"
                data-wechat="/blog/img/wechat.png" data-alipay="/blog/img/alipay.png">
            <div class="reward-toggle-ctrol">
                <span class="reward-toggle-item wechatPay">&nbsp;&nbsp;微信&nbsp;&nbsp;</span>
                <span class="reward-toggle-item alipayPay">支付宝</span>
            </div>
        </label>
        
        <i class="icon icon-caret-up"></i>
    </div>
</div>


    
    <div class="mask" id="mask"></div>
<a href="javascript:;" id="gotop" class="waves-effect waves-circle waves-light"><span class="icon icon-lg icon-chevron-up"></span></a>



<div class="global-share" id="globalShare">
    <ul class="reset share-icons">
      <li>
        <a class="weibo share-sns" target="_blank" href="http://service.weibo.com/share/share.php?url=https://nefelibata.icu/2022/063572401b.html&title=《LeetCode笔记-字符串》 — Nefelibata&pic=https://nefelibata.icu/img/avatar.jpg" data-title="微博">
          <i class="icon icon-weibo"></i>
        </a>
      </li>
      <li>
        <a class="weixin share-sns wxFab" href="javascript:;" data-title="微信">
          <i class="icon icon-weixin"></i>
        </a>
      </li>
      <li>
        <a class="qq share-sns" target="_blank" href="http://connect.qq.com/widget/shareqq/index.html?url=https://nefelibata.icu/2022/063572401b.html&title=《LeetCode笔记-字符串》 — Nefelibata&source=字符串" data-title=" QQ">
          <i class="icon icon-qq"></i>
        </a>
      </li>
      <li>
        <a class="facebook share-sns" target="_blank" href="https://www.facebook.com/sharer/sharer.php?u=https://nefelibata.icu/2022/063572401b.html" data-title=" Facebook">
          <i class="icon icon-facebook"></i>
        </a>
      </li>
      <li>
        <a class="twitter share-sns" target="_blank" href="https://twitter.com/intent/tweet?text=《LeetCode笔记-字符串》 — Nefelibata&url=https://nefelibata.icu/2022/063572401b.html&via=https://nefelibata.icu" data-title=" Twitter">
          <i class="icon icon-twitter"></i>
        </a>
      </li>
      <li>
        <a class="google share-sns" target="_blank" href="https://plus.google.com/share?url=https://nefelibata.icu/2022/063572401b.html" data-title=" Google+">
          <i class="icon icon-google-plus"></i>
        </a>
      </li>
    </ul>
 </div>


<div class="page-modal wx-share" id="wxShare">
    <a class="close" href="javascript:;"><i class="icon icon-close"></i></a>
    <p class="wechatshare">扫一扫，分享到微信</p>
    <img src="" alt="微信分享二维码">
</div>




    <!-- waves按钮特效 -->
<script src="//cdn.bootcss.com/node-waves/0.7.4/waves.min.js"></script>

<!-- 主题配置脚本 -->
<script>
var BLOG = { ROOT: '/blog/', SHARE: true, REWARD: true };
</script>

<!-- jquery -->
<script src="/blog/js/jquery.min.js?v=3.0"></script>

<!-- 搜索 -->

<div class="search-panel" id="search-panel">
    <ul class="search-result" id="search-result"></ul>
</div>
<template id="search-tpl">
<li class="item waves-block waves-effect" onclick="location.href='{path}'">
    <div class="title ellipsis" title="{title}">{title}</div>
</li>
</template>


<!-- main博客脚本 -->
<script src="/blog/js/main.min.js?v=3.0" ></script>

<!-- 动画&配置 -->
<script src="/blog/js/script.min.js?v=3.0" ></script>

<!-- 脚本管理 -->
<script>

if(window.innerWidth > 800){
	/* 3D标题 */
	$(".content-header").on("mousemove", threedee);

	/* 底部追随鼠标 */
	$(".footer").hover(2);

	/* gotop键的涟漪 */
	$("#gotop").hover(1);

	/* 赞赏的粒子雨 */
	$("#reward").hover(3);

	/* 微信公众号的底部渲染 */
	$("#wechat").hover(4);

    /* 标题跳动 */
    $(".archivestitle").bumpyText();

	/* 图片点击放大 */
	const postimg = jQuery(".post-content img:not(.github-emoji)");
	postimg.on("click",function(){

		mask.classList.add("in");
		main.classList.add("Mask");
		menu.classList.add("Mask");
		var myimg = this.cloneNode(true);
		myimg.classList.add("imgShow");

		setTimeout(function(){
			jQuery(myimg).animate({
				opacity:"1"
			},1000);
		},0);

		document.body.appendChild(myimg);

		myimg.onclick=function(){
			document.body.removeChild(myimg);
			mask.classList.remove("in");
			main.classList.remove("Mask");
			menu.classList.remove("Mask");
		};

	});

}

/* 名字跳动 */
$("#name").bumpyText();


/* 网站运行时间 */
// setInterval(function () {
// 	setTime("2021/3/27");
// }, 1000);

/* 文章块的淡出 */
postshow();

/* 座右铭 */
// 
//    getHitokoto();
// 


/* 粘贴提示 */
G($(".post-content"), location.href, "Nefelibata");


/* 控制台 */
if (window.console && window.console.log) {
	setTimeout(function () {
		console.log("\n %c Nefelibata %c  © kpl0111  http://nefelibata.icu \n\n", "color:#FFFFFB;background:#1abc9c;padding:5px 0;border-radius:.5rem 0 0 .5rem;", "color:#FFFFFB;background:#080808;padding:5px 0;border-radius:0 .5rem .5rem 0;");
	}, 0);
}

</script>




<!-- 公式渲染 -->

<!-- mathjax config similar to math.stackexchange -->

<script type="text/x-mathjax-config">
MathJax.Hub.Config({
    tex2jax: {
        inlineMath: [ ['$','$'], ["\\(","\\)"]  ],
        processEscapes: true,
        skipTags: ['script', 'noscript', 'style', 'textarea', 'pre', 'code']
    }
});

MathJax.Hub.Queue(function() {
    var all = MathJax.Hub.getAllJax(), i;
    for(i=0; i < all.length; i += 1) {
        all[i].SourceElement().parentNode.className += ' has-jax';
    }
});
</script>

<script async src="//cdn.bootcss.com/mathjax/2.7.0/MathJax.js?config=TeX-MML-AM_CHTML" async></script>



<!-- 不蒜子 -->
<!--  -->

</body>
</html>
